scholarly journals Experimental study on the explosion characteristics of hydrogen-methane premixed gas in complex pipe networks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinzhang Jia ◽  
Yinuo Chen ◽  
Guangbo Che ◽  
Jinchao Zhu ◽  
Fengxiao Wang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Flame Temperature ◽  
Flame Velocity ◽  
Pipe Network ◽  
Fuel Gas ◽  
Pipe Networks ◽  
Gas Explosions ◽  
Explosion Overpressure ◽  
Evolution Laws ◽  
And Control

AbstractTo explore the overpressure evolution laws and flame propagation characteristics in complex pipe networks after the addition of hydrogen to methane, we experimentally studied the explosive pressure wave and flame wave propagation laws for three different premixed gas mixtures with hydrogen-methane concentrations of 0, 10% and 20% when the equivalence ratio was 1. Experimental results indicate that the maximum explosion overpressure of the premixed gas increases with increasing distance from the explosion source, and it shows a gradually decreasing trend. In the complex pipe network, an overpressure zone is formed in the B–E–H and D–E sections of the network. The flame temperature is superimposed with the superimposition of the pressure, showing a trend of first increasing, then decreasing, then increasing, and finally decreasing in the complex pipe network. The flame arrival time increases with increasing distance, and the maximum flame speed shows a decreasing trend. The peak overpressure and maximum flame velocity of the premixed gas under a hydrogen volume fraction of 20% are 1.266 MPa and 168 m/s. The experimental research results could provide important theoretical guidelines for the prevention and control of fuel gas explosions in urban pipe networks.

scholarly journals Experimental Study On The Explosion Characteristics of Hydrogen-methane Premixed Gas in Complex Pipe Networks

2021 ◽  
Author(s):  
Jinzhang Jia ◽  
Yinuo Chen ◽  
Guangbo Che ◽  
Jinchao Zhu ◽  
Fengxiao Wang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Flame Temperature ◽  
Flame Velocity ◽  
Pipe Network ◽  
Fuel Gas ◽  
Pipe Networks ◽  
Gas Explosions ◽  
Explosion Overpressure ◽  
Evolution Laws ◽  
And Control

Abstract To explore the overpressure evolution laws and flame propagation characteristics in complex pipe networks after the addition of hydrogen to methane, we experimentally studied the explosive pressure wave and flame wave propagation laws for three different premixed gas mixtures with hydrogen-methane concentrations of 0, 10% and 20% when the equivalence ratio was 1. Experimental results indicate that the maximum explosion overpressure of the premixed gas increases with increasing distance from the explosion source, and it shows a gradually decreasing trend. In the complex pipe network, an overpressure zone is formed in the B-E-H and D-E sections of the network. The flame temperature is superimposed with the superimposition of the pressure, showing a trend of first increasing, then decreasing, then increasing, and finally decreasing in the complex pipe network. The flame arrival time increases with increasing distance, and the maximum flame speed shows a decreasing trend. The peak overpressure and maximum flame velocity of the premixed gas under a hydrogen volume fraction of 20% are 1.266 MPa and 168. The experimental research results could provide important theoretical guidelines for the prevention and control of fuel gas explosions in urban pipe networks.

Design a PLC-Based Variable-Frequency Governing Pressure-Constant Water-Supply Control System

2014 ◽  
Vol 1044-1045 ◽  
pp. 755-758
Author(s):  
Xin Hui Yang
Keyword(s):  
Control System ◽  
Water Supply ◽  
Pressure Sensors ◽  
Variable Frequency ◽  
Pipe Network ◽  
Monitoring And Control ◽  
Control Software ◽  
Industrial Control ◽  
Time Basis ◽  
And Control

This paper provides a design for a PLC-based, variable-frequency governing, pressure-constant, automatic water-supply control system. This design is based on the current situations at the water supply plants found in small and medium cities in China. In this control system, the pressure signal across the pipe network is acquired by pressure sensors and then transmitted to PID modules in the PLC in order to control switching between pump motors. At the same time, the PLC is connected with a personal computer for industrial control purposes. On this computer, monitoring and control software has been installed in order to monitor and control the pressure-constant water-supply system on a real-time basis.

scholarly journals Effects of vertebroplasty on endplate subsidence in elderly female spines

2015 ◽  
Vol 22 (3) ◽  
pp. 273-282 ◽  
Author(s):  
Srinidhi Nagaraja ◽  
Hassan K. Awada ◽  
Maureen L. Dreher ◽  
John T. Bouck ◽  
Shikha Gupta
Keyword(s):  
Bone Cement ◽  
Trabecular Bone ◽  
Volume Fraction ◽  
Micro Ct ◽  
Control Groups ◽  
Bone Volume Fraction ◽  
Elderly Female ◽  
Maximum Subsidence ◽  
And Control ◽  
Adjacent Vertebra

OBJECT The aim in this study was to quantify the effects of vertebroplasty on endplate subsidence in treated and adjacent vertebrae and their relationship to endplate thickness and underlying trabecular bone in elderly female spines. METHODS Vertebral compression fractures were created in female cadaveric (age range 51–88 years) thoracolumbar spine segments. Specimens were placed into either the control or vertebroplasty group (n = 9/group) such that bone mineral density, trabecular microarchitecture, and age were statistically similar between groups. For the vertebroplasty group, polymethylmethacrylate bone cement was injected into the fractured vertebral body under fluoroscopy. Cyclic compression (685–1370 N sinusoid) was performed on all spine segments for 115,000 cycles. Micro-CT scans were obtained before and after cyclic loading to quantify endplate subsidence. Maximum subsidence was compared between groups in the caudal endplate of the superior adjacent vertebra (SVcau); cranial (TVcra) and caudal (TVcau) endplates of the treated vertebra; and the cranial endplate of the inferior adjacent vertebra (IVcra). In addition, micro-CT images were used to quantify average endplate thickness and trabecular bone volume fraction. These parameters were then correlated with maximum endplate subsidence for each endplate. RESULTS The maximum subsidence in SVcau endplate for the vertebroplasty group (0.34 ± 0.58 mm) was significantly (p < 0.05) greater than for the control group (−0.13 ± 0.27 mm). Maximum subsidence in the TVcra, TVcau, and IVcra endplates were greater in the vertebroplasty group, but these differences were not significant (p > 0.16). Increased subsidence in the vertebroplasty group manifested locally in the anterior region of the SVcau endplate and in the posterior region of the TVcra and TVcau endplates (p < 0.10). Increased subsidence was observed in thinner endplates with lower trabecular bone volume fraction for both vertebroplasty and control groups (R2 correlation up to 62%). In the SVcau endplate specifically, these 2 covariates aided in understanding subsidence differences between vertebroplasty and control groups. CONCLUSIONS Bone cement injected during vertebroplasty alters local biomechanics in elderly female spines, resulting in increased endplate disruption in treated and superior adjacent vertebrae. More specifically, bone cement increases subsidence in the posterior regions of the treated endplates and the anterior region of the superior caudal endplate. This increased subsidence may be the initial mechanism leading to subsequent compression fractures after vertebroplasty, particularly in vertebrae superior to the treated level.

Properties of TiC-Ni Based Coatings Deposited by Different HVOF Spraying

2000 ◽  
Author(s):  
P. Vuoristo ◽  
M. Väisänen ◽  
T. Mäntylä ◽  
L.-M. Berger
Keyword(s):  
Wear Resistance ◽  
Flame Temperature ◽  
Oxygen Flow ◽  
Spray Parameters ◽  
Coating Properties ◽  
Hvof Spraying ◽  
Fuel Gas ◽  
Wear Rates ◽  
Operation Conditions ◽  
Satisfactory Coating

Abstract Hardmetal-like coatings of the TiC-Ni system are potential for use as wear, corrosion and heat resistant coatings in various operation conditions. Our previous works [1-12] have shown that these materials are well sprayable using different thermal spray processes such as plasma, D-Gun and HVOF spraying. Since HVOF spraying is today the most important process used to apply carbide based coatings, this study was carried out in order to evaluate more systematically the sprayability of these novel spray powders and the influence of HVOF spray parameters on some coating properties. Coating samples were prepared by using DJ Hybrid gun with propane as a fuel gas, and a CDS gun with hydrogen fuel gas. Oxygen flow rate was varied in both cases for changing the flame temperature. Microstructure, phase composition, hardness, and abrasion wear resistance of the coated samples were investigated. The results showed that both HVOF processes used give satisfactory coating properties and that the use of high oxygen flow rates is beneficial for improving the wear resistance of the coatings. Powders with fine particle size are beneficial in the DJ Hybrid process; the use of coarse powders results in coatings with somewhat higher wear rates. The optimum spray condition for the TiC-Ni system powders differs from that typically used for conventional WC-Co and Cr3C2-NiCr powders by a higher flame temperature.

Theoretical Assessment of Convective and Radiative Heat Losses in a One-Dimensional Multiregion Premixed Flame With Counter-Flow Design Crossing Through Biofuel Particles

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Mehdi Bidabadi ◽  
Saman Hosseinzadeh ◽  
Sadegh Sadeghi ◽  
Mostafa Setareh
Keyword(s):  
Temperature Profile ◽  
Radiative Heat ◽  
Flame Structure ◽  
Flame Temperature ◽  
Heat Losses ◽  
Flame Velocity ◽  
Mass Fractions ◽  
Interface Matching ◽  
Energy Balances ◽  
Stagnation Plane

Due to perspective of biomass usage as a viable source of energy, this paper suggests a potential theoretical approach for studying multiregion nonadiabatic premixed flames with counterflow design crossing through the mixture of air (oxidizer) and lycopodium particles (biofuel). In this research, convective and radiative heat losses are analytically described. Due to the properties of lycopodium, roles of drying and vaporization are included so that the flame structure is created from preheating, drying, vaporization, reaction, and postflame regions. To follow temperature profile and mass fraction of the biofuel in solid and gaseous phases, dimensionalized and nondimensionalized forms of mass and energy balances are expressed. To ensure the continuity and calculate the positions of drying, vaporization, and flame fronts, interface matching conditions are derived employing matlab and mathematica software. For validation purpose, results for temperature profile is compared with those provided in a previous research study and an appropriate is observed under the same conditions. Finally, changes in flame velocity, flame temperature, solid and gaseous fuel mass fractions, and particle size with position measured from the position of stagnation plane, strain rate, and heat transfer coefficient in the presence/absence of losses are evaluated.

Study on Distributed Intelligent Control Model of the Ships Pipe Network

2014 ◽  
Vol 904 ◽  
pp. 287-291
Author(s):  
Tao Jin ◽  
Ze Yuan Zhou ◽  
Feng Yang
Keyword(s):  
Intelligent Control ◽  
Control Model ◽  
Sensor Data ◽  
Pipe Network ◽  
Control Logic ◽  
Control Rules ◽  
Valve Leakage ◽  
Pipe Segment ◽  
And Control ◽  
Valve Control

A MAS-based distributed intelligent pipeline leakage control model, ship pipe network through the intelligent valve control system for automatic, independent isolate damaged sections, thereby enhancing ship in wartime circumstances viability. According to distributed intelligent control pipe network model composed of properties, the Agent is divided into sensor Agent, processors and actuators Agent. Agent of the processor by the sensor data collected Agent independent judgment pipe segment status judgment method and control rules proposed intelligent valve leakage indicator to determine the logic of the other characteristic parameters for a comparative study. Pipeline leakage numerical simulation results show that: the model and control logic to isolate leakage pipe sections, using the model can improve the vitality of ship pipe network.

An experimental study on thermal radiation of fire whirl

2017 ◽  
Vol 26 (8) ◽  
pp. 693 ◽  
Author(s):  
Pengfei Wang ◽  
Naian Liu ◽  
Yueling Bai ◽  
Linhe Zhang ◽  
Kohyu Satoh ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Flame Temperature ◽  
Soot Volume Fraction ◽  
Measured Data ◽  
Emissive Power ◽  
Air Curtain ◽  
Power Profile ◽  
Flame Emissivity ◽  
Fire Whirl ◽  
Infrared Methods

Fire whirl is frequently observed in wildland fires, and may cause serious difficulty in firefighting owing to its significant turbulent flow. In this paper, the radiation of fire whirl is investigated through experiments using a fire whirl facility made up of an air curtain apparatus, with five different sizes of n-heptane pools (25, 30, 35, 40 and 45 cm). The flame contour was extracted by image processing. By using infrared methods, the flame emissivity of fire whirl at different heights for different pool diameters was measured, and thereby a correlation was developed between the flame emissivity and the flame diameter. The soot volume fraction in the luminous flame is estimated to range within 2.5 × 10−6 to 4.0 × 10−6, much higher than that of general heptane pool fires, which provides an explanation of the higher flame emissivity of fire whirl. The emissive power profile v. normalised height is deduced from flame emissivity and flame temperature data. A multizone flame model (in which each zone is assumed as a grey body) is used, based on the measured data of flame emissivity, to predict the radiation of fire whirl. Comparison between the predicted and measured data of radiative flux shows good agreement.

scholarly journals Texture and Microstructure Development in Al2O3-Platelet Reinforced Ce-ZrO2/Al2O3 Laminates Produced by Centrifugal Consolidation

1995 ◽  
Vol 24 (1-3) ◽  
pp. 43-52 ◽  
Author(s):  
Ryan K. Roeder ◽  
Keith J. Bowman ◽  
Kevin P. Trumble
Keyword(s):  
Microstructural Evolution ◽  
Volume Fraction ◽  
Phase Segregation ◽  
Functionally Gradient ◽  
Property Evaluation ◽  
Quantitative Image ◽  
Microstructural Design ◽  
Efficient Packing ◽  
And Control ◽  
Platelet Content

A dispersed, low-solids-fraction suspension containing Ce-ZrO2, fine Al2O3 and 5 vol% Al2O3-platelets was segregated using centrifugal consolidation to produce functionally gradient laminates (FGLs). Platelet alignment facilitated efficient packing of highly anisometric platelets to high densities. The complexity and anisotropy of the microstructure warrants a quantitative analysis of the microstructural evolution prior to any property evaluation. Quantitative image analysis was used to examine changes in the volume fraction, dimensional anisotropy, and gradient of pores and platelets with sintering time. In all cases, special attention was given to the effects of texture during microstructural evolution. Platelet alignment enhanced densification via anisotropic shrinkage, overcoming constraint that otherwise inhibits densification in platelet-containing materials. Also, platelet alignment and microstructural design were used to initiate and control anisotropic grain growth. Platelet growth (at the expense of smaller particles of the same phase) during annealing promoted further phase segregation and produced higher platelet content composites consisting of larger platelets, without having to consolidate high contents of large platelets.

Pressure and flow propagation rule beyond original premixed area of methane-air in tunnel

2014 ◽  
Vol 24 (8) ◽  
pp. 1626-1635 ◽  
Author(s):  
Qi Zhang ◽  
Qiuju Ma
Keyword(s):  
Numerical Simulation ◽  
Flame Propagation ◽  
Volume Fraction ◽  
Ignition Point ◽  
Content Type ◽  
Explosion Overpressure ◽  
Air Explosion ◽  
Propagation Rule ◽  
Flow Propagation ◽  
Propagation Rules

Purpose – Whether a fire can be initiated in an explosion accident depends on the explosion and deflagration process. In the methane-air explosion in a tunnel, the flame accelerates from the ignition point. However, where it begins to decelerate is not clear. The purpose of this paper is to examine the explosion overpressure, flow and flame propagation beyond the premixed area of methane-air in a tunnel. Design/methodology/approach – The numerical simulation was used to study the explosion processes of methane-air mixtures in a tunnel. Based on the numerical simulation and its analysis, the explosion overpressure, flow and flame propagation rules beyond the premixed area were demonstrated for a methane-air explosion. Findings – The peak overpressure of methane-air mixture explosion was observed to reach its maximum beyond the original premixed area of methane-air. The hazardous effects beyond the premixed area may be stronger than those within the premixed area for a methane-air explosion in a tunnel. Under the conditions of this study, the ratio between the length of combustion area (40 m) and that of original premixed area (28 m) reaches 1.43. Originality/value – Little attention has been devoted to investigating the explosion overpressure, flow and flam propagations beyond the original premixed area of methane-air in a tunnel. Based on the numerical simulation and the analysis, the propagation rule of overpressure wave and flow inside and outside the space occupied by methane/air mixture at the volume fraction of 9.5 percent in a tunnel were obtained in this work.

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